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