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