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