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