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