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