One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,6,5)(3,4,8,7)(10,14)(15,17)(16,20)(22,23)(1,3)(2,7)(4,5)(6,8)(9,10)(11,17)(12,16)(13,14)(15,18)(19,23)(20,21)(22,24)(25,26)(27,32)(28,29)(30,31)(33,37)(34,38)(35,40)(36,39) involution — undirected(1,4,6,7)(2,3,5,8)(11,18)(15,17)(19,24)(22,23)(26,31)(28,37)(32,39)(34,40)(2,5)(3,8)(9,10)(11,15)(12,20)(13,14)(16,21)(17,18)(19,23)(22,24)(25,27)(26,32)(28,34)(29,38)(30,36)(31,39)(33,35)(37,40) involution — undirected(1,4)(2,3)(5,8)(6,7)(9,11)(10,15)(12,19)(13,18)(14,17)(16,22)(20,23)(21,24)(25,28)(26,33)(27,34)(29,31)(30,37)(32,35)(36,40)(38,39) involution — undirected(1,5,6,2)(3,4,8,7)(9,12)(10,16)(11,19)(13,21)(14,20)(15,22)(17,23)(18,24)(25,29,30,33)(26,28,31,37)(27,35,36,38)(32,40,39,34)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.