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