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)(11,23)(12,27)(13,30)(14,21)(15,20)(16,22)(17,25)(18,28)(19,24)(26,36)(29,35)(31,40)(32,39)(33,37)(34,38) involution — undirected(1,3,5,4)(2,6,7,8)(9,11,16,26)(10,17,22,37)(12,13,29,32)(14,33,15,25)(18,30,38,39)(19,27,40,35)(20,36,21,23)(24,34,31,28)(1,4,5,3)(2,6,7,8)(9,12,16,29)(10,18,22,38)(11,24,26,31)(13,25,32,33)(14,34,15,28)(17,19,37,40)(20,35,21,27)(23,30,36,39)(9,13,15,24,16,32,14,31)(10,19,21,30,22,40,20,39)(11,12,25,28,26,29,33,34)(17,35,23,18,37,27,36,38)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.