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