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