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