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