One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,7)(6,8)(9,10)(11,12)(13,15)(14,21)(16,18)(17,22)(19,24)(20,23)(25,26)(27,34)(28,32)(29,31)(30,35)(33,38)(36,40)(37,39) involution — undirected(1,2,5,3)(4,6,8,7)(9,11,15,16)(10,12,13,18)(14,19,22,23)(17,20,21,24)(25,27,30,29)(26,31,35,34)(28,36,38,37)(32,39,33,40)(1,2,5,3)(4,6,8,7)(9,12,15,18)(10,16,13,11)(14,20,22,24)(17,23,21,19)(25,28,30,38)(26,32,35,33)(27,36,29,37)(31,39,34,40)(2,3)(6,7)(9,12)(10,11)(13,16)(14,20)(15,18)(17,19)(21,23)(22,24)(25,28)(26,33)(27,36)(29,37)(30,38)(31,40)(32,35)(34,39) involution — undirected(1,3,5,2)(4,7,8,6)(9,13,15,10)(11,18,16,12)(14,21,22,17)(19,24,23,20)(25,26)(27,31)(28,32)(29,34)(30,35)(33,38)(36,39)(37,40)(1,4)(2,6)(3,7)(5,8)(9,14,15,22)(10,17,13,21)(11,19,16,23)(12,20,18,24)(25,29,30,27)(26,34,35,31)(28,37,38,36)(32,40,33,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.