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