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