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