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