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