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