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